1. Field of the Invention
The present invention relates to an ink-jet print head for ejecting a liquid used for printing to a printing surface of a printing medium to perform printing operation and a production method of the ink-jet print head.
2. Description of Prior Art
An ink-jet printing apparatus is generally provided with a print head for ejecting an ink as a liquid used for printing. The print head, for example, as shown in FIG. 4, is fixed to an apparatus main body part 2 in the ink-jet printing apparatus through a support plate 8. The print head comprises an ink ejection part 12 having a plurality of relatively small ink ejection openings for ejecting ink droplets ID to the printing surface of paper Pa and a printed circuit board 10 provided on the support plate 8 for supplying drive control signals to heaters provided in respective ink flow passages communicating with the respective ink ejection openings of the ink ejection part 12.
A connection terminal 10A of the printed circuit board 10 is connected to a connector 4 of the apparatus main body part 2 outputting a drive control signal group. Further, transportation direction of paper Pa is, for example, a direction along a nearly perpendicular direction to the paper surface.
In the ink ejection part 12 one connection opening 12a communicating with a common liquid chamber for distributing ink to respective ink flow passages is connected to an end of an ink passage 16 constituting part of a component of a liquid supply device for supplying ink to the print head. Further, in the ink ejection part 12 the other connection opening 12b communicating with the common liquid chamber is connected to an end of an ink passage 18 constituting part of a component of the liquid supply device.
The other ends of the ink passages 16 and 18 are respectively connected to a head side joint part 14 engaged with a main body side joint part 6. The main body side joint part 6 has an ink passage supplied with ink from the apparatus main body part 2.
The head side joint part 14 has a filter containing chamber communicated with an inner peripheral part of the other end of the ink passage 16, and a filter containing chamber communicated with an inner peripheral part of the other end of the ink passage 18. Smaller end diameters of the tapered filter containing chambers are respectively the same as diameters of the inner peripheral parts, and larger end diameters thereof are almost the same as diameters of filters as straining members contained. Each filter is to collect foreign matters such as dust in the ink.
In the thus constructed print head, there is a fear that foreign matters such as cutting debris or dust in the production process exist in the ink passages.
In the print head, for example, as shown in FIG. 5, in which a plurality of ink flow passages 27 are formed by adjacent partition walls 22 with predetermined intervals provided in parallel to each other in the common liquid chamber 28, the print head is of a type in which electrothermal conversion elements 24 used for ejecting ink are provided in each ink flow passage 27 to eject ink in the direction shown by the arrow, namely, along an extension direction of the ink passage 27 through the ejection opening 26. In this type of print head, when the common liquid chamber 28 or the ink flow passage 27 is constructed by a method of cutting such as cutting, cutting debris 23 is generated, which may exist at an inlet part (upstream side end part) of the ink flow passage 27 or in the common liquid chamber 28.
Further, also in the print head of a type as shown in FIG. 6, in which in its orifice plate OP, an ejection opening 26xe2x80x2 is provided at a position opposing each electrothermal conversion device 24xe2x80x2 provided in each ink flow passage 27xe2x80x2 , and ink is ejected through the ejection opening 26xe2x80x2 , in the direction shown by the arrow, namely in a direction opposing the electrothermal conversion device 24xe2x80x2, similarly to the above, there is a possibility that cutting debris 23 generated in the production of the print head remain in each ink flow passage 27xe2x80x2 and the common liquid chamber 28 of the completed head.
Yet further, there is known, as shown in FIGS. 7 and 8, a print head having ejection openings 26 in an order of thousands. In FIGS. 7 and 8, same components as those shown in FIGS. 4 and 5 are indicated with the same reference numbers, and detailed description there is omitted.
In the print head as shown in FIGS. 7 and 8, the ink ejection part 12 comprises a substrate 13 having electrothermal conversion devices 24 corresponding to respective ink flow passages 27 and electrically connected to the printed circuit board 10, and a top plate 11 respectively having ejection openings 26 communicating with the respective ink flow passages 27.
In such a print head, there may be a case that a relative position of the electrothermal conversion device 24 at the substrate 13 side is shifted with respect to the ink flow passage 27 due to a difference in thermal expansion coefficient between a material of the top plate 11 and that of the substrate 13.
As a method for eliminating this problem, a method is proposed in which to improve a problem of thermal contraction during processing of the print head, the top plate 11 which forms the ink flow passage 27 in cooperation with the substrate 13 is, for example, insert formed with a stainless pipe 31 or the like.
In the print head thus fabricated by the above method, to obtain a structure capable of ink supply, the stainless pipe 31 is provided with a drilling hole 29 communicating with the common liquid chamber 28 at an appropriate interval, utilizing the stainless pipe 31 as a passage 33 for flowing ink in the stainless pipe 31.
Therefore, cutting debris 23 generated during the machining may exist at. the inlet of the ink flow passage 27 and in the common liquid chamber 28.
Such a foreign matter generated during machining may disturb ink flow at the inlet part of the ink flow passage 27 or in the common liquid chamber 28 and result in degradation of ink ejection performance. This leads to a reduction of yield of the produced print heads.
In order to remove cutting debris existing inside the print head just described, it is necessary to clean the inside of the print head. Further, in order to perform the cleaning more certainly, it is preferable to construct the print head such that the route for discharging cutting debris from the inside of the print head to the outside be appropriately selected depending on the size or the like of cutting debris existing in the inside.
It is an object of the present invention to provide an ink-jet print head capable of efficiently discharging cutting debris or the like from the inside of the print head to the outside, in which, in the production of the print head, a process is employed for cleaning the inside of the print head.
A further object of the present invention is to provide an ink-jet print head having a configuration capable of performing cleaning of the inside of the print head with ease.
In accordance with the present invention which is proposed to attain the above objects, there is provided a production method of an ink-jet print head comprising a plurality of ejection openings for ejecting a liquid, liquid flow passages for supplying the liquid to each of the plurality of ejection openings, a common liquid chamber communicating with the plurality of liquid flow passages, a first liquid passage communicating with one end of the common liquid chamber and having a diameter larger than that of the liquid flow passage, a second liquid passage communicating with the other end of the common liquid chamber and having a diameter larger than that of the liquid flow passage, and an openable/closable opening part having an opening diameter larger than that of the liquid flow passage provided halfway in the second liquid passage.
The print head is characterized in that the print head is produced employing a process for screening a foreign matter larger than the opening diameter of the liquid flow passage generated in the liquid passages, the liquid flow passages, or the common liquid chamber by a difference of opening diameter of the liquid flow passages.
Further, the ink-jet print head according to the present invention is characterized by comprising a plurality of nozzles for ejecting an ink, ink flow passages for supplying the ink to the plurality of nozzles, a common liquid chamber communicating with the plurality of ink flow passages, a first ink passage provided with a first filter at the other end side of a communicating part communicating with one end of the common liquid chamber, and a second ink passage provided with a second filter at the other end side of a communicating part communicating with the other end of the common liquid chamber, wherein an openable/closable opening having an opening diameter larger than that of the ink flow passage is provided halfway in the second ink passage.
Further, the present invention is characterized by comprising a first passage provided with arranged liquid ejection openings for ejecting a liquid used for printing communicating with one end side in a liquid ejection part for conducting the liquid into the liquid ejection part, a second passage communicating with the other end side of the liquid ejection part for supplying the liquid to the liquid ejection part or conducting out the liquid inside the liquid ejection part, and open/close means provided halfway in the second passage for communicating inside of the second passage selectively with the outside to discharge the liquid in the second passage to the outside.
As apparent from the above description, according to the print head and the production method of the ink-jet print head, since open/close means for selectively communicating the inside of the second ink passage with the outside is provided halfway in the second ink passage to discharge the liquid in the second ink passage, an unnecessary foreign matter remaining in the ink flow passage can be removed certainly and simply from the inside of the ink flow passage.
Since a cleaning liquid discharge part provided halfway in the ink passage is constructed to have an opening diameter larger than that of the ink flow passage communicating with the ink ejection opening, in performing treatment of foreign matter existing inside the print head, a foreign matter that can be discharged from the ink flow passage and a foreign matter of a size that cannot be discharged from the ink flow passage are separated by a difference in opening diameter, it is possible that the large foreign matter is discharged to the outside through the ink flow passage, and the small foreign matter is certainly discharged from the ink flow passage.
Further, foreign matter in the ink flow passage is even more certainly discharged to the outside by sucking from the ejection opening side.
A connector cap or a select valve provided at the cleaning liquid discharge part simplifies the configuration to communicate the ink passage or cut off the ink passage to release it to the outside according to the processing to be performed by the print head.
In cleaning of the print head, by vibrating the print head, since foreign matter can be effectively peeled off from the inner wall part of the print head and efficiently moved along with the cleaning liquid, cleaning effect is improved and, therefore, number of defective print heads causing non-ejection is reduced, and yield in the production of the print head is improved.
The above and other objects, effects, features and advantages of the present invention will become more apparent from the following description of embodiments thereof taken in conjunction with the accompanying drawings.